摘要:
The present invention relates to a method and apparatus of determining the rheological properties of a polymer flowing in a conduit. The invention provides a method of characterising a polymer under test, comprising: Detecting acoustic emissions from said polymer flowing in a conduit to provide acoustic emission data, comparing the acoustic emissions data obtained against acoustic emission data from a polymer, or a series of polymers, of known characteristics, and thereby characterising the polymer.
摘要:
A method of compounding a multimodal, preferably a bimodal polymer composition comprising a low molecular weight ethylene polymer and a high molecular weight ethylene polymer is described. The composition is compounded during a relatively long time at a low temperature which lies in a narrow temperature range including the melting point of the low molecular weight ethylene polymer. More particularly, the polymer composition is compounded, without addition of a beat transfer medium, in a temperature range from about 10.degree. C. below to about 10.degree. C. above the melting point of the low molecular weight ethylene polymer during a time of more than 10 seconds. The viscosity ratio between the ethylene polymers in said temperature range preferably is from about 5:1 to about 1:5.
摘要:
The present invention relates to a polyethylene composition wherein (i) the composition has an MFR2 of 0.05 to 100 g/10 min, (ii) the environmental stress crack resistance ESCR measured in hours according to ASTM 1693, condition B and E-modulus EM measured according to ISO 527-2: 1993 in MPa satisfy the following relation: ESCR>−EM h/MPa+1150 h.
摘要:
A method and apparatus for studying the properties of a fluid are provided in which in which a rheometer is used to obtain, for example, value(s) indicative of the shear stress in the fluid to thereby obtain a set of data. The data is then directly compared using, for example, multivariate analysis, with previously obtained data corresponding to a fluid(s) with known rheological properties. The results of this comparison can then be used, for example, to control a manufacturing process.
摘要:
A method of homogenizing polypropylene using twin counter-rotating screws with a melting stage and a separate downstream mixing phase. The polypropylene is melted to at least 5° C. above its melting point in the melting stage and passed through a gate valve into the mixing section. The elongational stress applied to the polymer in the mixing section is at least 20% greater than that of conventional counter-rotating extruders and causes a Henchy strain of between 1.5 and 2.5 in the polymer. This causes significant strain hardening within the polymer sufficient to break up gels within the polypropylene, thereby producing a polymer with no visible white spots.
摘要:
The present invention relates to a polyethylene composition wherein (i) the composition has an MFR2 of 0.05 to 100 g/10 min, (ii) the environmental stress crack resistance ESCR measured in hours according to ASTM 1693, condition B and E-modulus EM measured according to ISO 527-2: 1993 in MPa satisfy the following relation: ESCR>−EM h/MPa+1150 h.
摘要:
The use in the manufacture of a polyethylene article of a polyethylene composition comprising 20 to 50% wt of a copolymer of ethylene and a C3-20 alpha olefin comonomer and 50 to 80% wt. Of a lower weight average molecular weight ethylene polymer, the polyethylenes of the composition together having a density of 935 to 965 kg/m3, weight average molecular weight of 60000 to 300000 g/mol, an MFR2.16 at 190° C. of 0.1 to 10 g/10 min., and a molecular weight distribution (MWD) of from 2.5 to 20, the copolymer having a comonomer content of from 0.006 to 9 mol % and a degree of branching of 0.03 to 45 branches per 1000 carbons, and the ethylene polymer having a density of 939 to 975 kg/m3 and a weight average molecular weight of 20000 to 200000 g/mol.